In order to decrease the weight of electronic devices and to ease an increase in weight due to enlarged liquid crystal display devices, it has been demanded to decrease the thickness of polarizing plates. However, when a liquid crystal display device is enlarged, it becomes difficult to have the polarizing plate to properly adhere onto the liquid crystal cells due to curling and deformation.
For example, in Patent Document 1, proposed is a polarizing plate employing a thin, layered polarizer, whereby a decrease in curling and deformation is described. However, since this method significantly differs from the conventional polarizing plate production process, problems of poor productivity have been exhibited. Further, when a thin, layered polarizing plate is adhered onto a liquid crystal panel, employing a polarizing plate protective film provided with a retardation film function, problems have tended to occur.
Still further, in Patent Document 2, proposed as a polarizing plate protective film, provided with a retardation film function, is an optical compensation sheet at a layer thickness of 10-70 μm. It has been recognized that light leakage is markedly minimized by decreasing the photoelastic modulus of the optical compensation sheet and distortion due to variation of ambient conditions. However, even though the described polarizing plate employs an 80 μm thick polarizing plate protective film on the surface side, the decrease in weight is still insufficient since a thinner layer is employed only on the compensation sheet side. Further, problems have occurred in which curling tends to result due to the significant difference in thickness between the front and rear layers.
In Patent Document 3, proposed is a cellulose ester film of which breakage elongation is controlled within the range of 40-100% by the addition of polyester urethane. However, when the described method is employed, it is necessary to increase the thickness to achieve the desired birefringence value, whereby it has been difficult to decrease the weight by reducing the thickness of the polarizing plate.
In these described methods, it has clearly been seen that when a thin, layered polarizing plate, the total layer of which thickness is decreased by reducing the thickness of a polarizing plate protective film and a polarizer, is adhered onto a large-sized liquid crystal panel, problems tend to occur in which air bubbles tend to be included due to curling and deformation, and positioning tends to shift during adhesion.
Namely, an object of the present invention is to overcome the above problems during adhesion of a thin-layer polarizing plate onto a liquid crystal panel.
(Patent Document 1) Japanese Patent Publication for Public Inspection (hereinafter referred to as JP-A) No. 2000-338329
(Patent Document 2) JP-A No. 2002-139621
(Patent Document 3) JP-A No. 2002-267846